Means for the aerodynamic braking of aircraft



Aug. 4, 1953 M. H. L. SEDILLE 2,647,367

MEANS FOR THE AERODYNAMIC BRAKING AIRCRAFT Filed Feb. 10, 1948 2Sheets-Sheet l R ga.

Aug. 4, 1953 M. H. SEDILLE 2,647,367

MEANS FOR THE AERODYNAMIC BRAKING OF AIRCRAFT Filed Feb. 10, 1948 2Sheets-Sheet 2 Fig.4.

Patented Aug. 4, 1953 UNITED] STATES PATENT. OFFICE t 2,647,367 I IMEANS FOR THE AERODYNAMIC BRAKING I or AIRCRAFT Marcel HJL. Sdille,Paris, lirance, assignor to Societe Rateau .,-(Societe France, acompanyof France Anonyme) Paris,

Application February 10, 1948, Ser ial No. 7,497 I In France March '21,1947 v 4 Claims. 1

It is known fact that reaction jet airplanes assume a considerable speedof progression when landing and that their stopping requires asubstantial travel after they have come into contact appear hereinafter.

As concerns the deflection of air towards the front beforeit passesthrough the combustion chambers, such a method shows the drawback ofmodifying the operative opening of the compressor and of requiring amodification in the injection of fuel in order to avoid the rise intemperature resulting normally from the reduction of the air output.Moreover the reduction in the output through the turbine reduces thespeed of the group and for any subsequent pick up, in thecase of afailure in the landing for instance, it is necessary to begin byreaccelerating the machine,

which may'require a certain time. Lastly, the braking action is not veryimportant by reason of the air expanded towards the front not beingheated and of the drop in pressure accompanying the reduction in speedand the increase of the compressor opening.

The arrangement that uses a forward deflection of thejet of exhaustgases from the turbine does not show these drawbacks but it requires aspecial shape for the reactio jet nozzle that is com parativelyintricate-and diflicult to control while furthermore leading duringnormal operation to a'certain loss of energy.

The present invention relates to a method that does not show thesedrawbacks and that allows even for a comparativelyimportant braking action the integral retaining of all the possibilities V of pick up of themachine; in other words it does not modify or modifies only to anegligible extent the speed, the temperature and the amount of fuelinjected. Furthermore, itrequires no modification in the aerodynamiccircuit during-- normal operation. I

According to this method, there is ejected simul-. taneously towards thefront, gas removed from the exhaust of the turbine and driving fluidremoved prior to admission into said turbine.

The invention covers also an arrangement for executing saidmethod andincluding the association of a by-pass for the exhaust gases of theturbine towards the front without any modification in the reaction jetnozzle serving for normal operation, with another by-p'ass returningtowards the front the gases fromthe combustion chambers before theirentrance into the turbine.

The following description with reference to accompanying drawings willallow understanding how the invention'may be embodied.

In said drawings:

Fig. 1 is a diagrammatic axial cross-section, on line I-I' of Figure 3,of an aircraft fuselage equipped with a reaction jet turbine includingan embodiment of the invention erative position.

' Fig. 2 shows the same fuselage with the arrangement according to theinvention in its operative position.

Fig". 3is a transverse cross-section through line III-J-II of Fig. 1.'

Figure 4 shows diagrammatically a plan view ofan aircraft provided witha braking device according to the invention.

The upper longitudinal half cross-section of Fig.' 1 shows thedeflection of the exhaust gases passing out of theturbine it beforeentering the propelling' reactionjet nozzle u. This deflection .isprovided through the channel a leading to a chamber b located to thefront of the fairing. Saidchamber includes at least one exhaust port forthe gases towards the front, which port is closed during normal"operation of the aircraft by a valve 0. This valve is actuated by meansof a piston d with a pneumatic or hydraulic control or through any otherdevice within the skill of the designer.

The lowerlongitudinal half cross-section of Fig. 1 shows the deflectiontowards, the front of the driving fluid removed from the combustionchamber ch. before or preferably after the. combustion in order toincrease the temperature of the gases and consequently the speed ofbraking. This deflection is performed through a channel e lead:

ing' to a chamber 1 providedwith at least one opening for the ejectionof the gases towards the front, said port being closed during normaloperation by'means of a valve g. Said valve is rigid with a piston hthat is also controlled as above through any suitable means such as apneumatic or hydraulic system.

The simultaneous actions of both deflection bypasses, are adapted to oneanother in order to obtain with a constant injection of fuel a rotaryshown in its inopspeed of the reaction jet turbine that is substantiallyunchanged as well as a temperature without any substantial variation atthe admission into the turbine.

This is possible as may well be understood from the followingdisclosure. The increase (by opening of c) in the cross-sectional areaof the output of the exhaust gases from the turbine reduces the exhaustcounter pressure; this leads to an increase in the drop of thermicenergy available in the turbine and if the output of motive gasessimultaneously by-passed through valve 9 before entering the turbine issuitably reckoned, taking into account the reduction in pressurementioned, there is no modification in the power delivered by saidturbine and thereby in its rotary speed. It is just possible to find acertain increase in the opening of the compressor and thereby a certainreduction in pressure. The lat-' ter does not modify substantially theoutput of air which in the case of an injection of fuel that isunvarying corresponds as desired to the keeping of the temperature ofthe gases at a constant value.

When the braking is to be performed, the operator proceeds with thesimultaneous control of the valves 0 and 9' opening the deflectionbypasses towards the front, said control being obtained through a singleoperation in order to satisfy the conditions of stability as disclosedhereinabove. To this end the fluid acting on the pistons d and h may becontrolled by a common hand-operated distributor c.

When the valves c and g are in their open position illustrated in Fig.2, the currents of braking gases follow the circuit illustrated by thearrows.

The control of this action may be a gradual one so as to obtain forinstance a zero thrust for full speed of the unit.

In order to make the engine pick up, the pilot has just to close theoutputs for the braking gases. The result thereof is that automaticallyafter a very short time that depends only on the inertia of the gasstreams, a forward thrust is produced that is equal to maximum thrust.

In the embodiment shown in the drawing the braking jets are directedparallel to the common axis of the compressor and of the turbine, butthey may be directed obliquely with respect to said axis.

For a greater clarity of the drawings, the outputs of gas towards thefront are shown as lying to the front of the reaction jet turbine, whichin the case of a single engine on the aircraft might inconvenience thepilot if the latter is seated behind these outputs or even further tothe rear. As a matter of fact the outputs of braking gases are notnecessarily bound to the propelling unit and may be located at any otherpart of the aircraft in particular in the wings; it is sufficienttherefor to provide the necessary connecting pipes. Figure 4 shows anarrangement of this kind wherein several chambers b and ,f are disposedinside the wings of an aircraft at points regularly spaced along theleading edge of said wings. The chambers 11 and f are connected byrespective pipes a and e to the exhaust side of the gas turbine t and tothe exit of the combustion chambers. The chambers 22 and 3 openfrontwardly on the leading edge and are provided with control valvessimilar to valves c and 9 described above. Such an arrangement shows theconsiderable advantage of allowing a setting of the braking effort thatsuits to the best d the stability of the aircraft, which is not the casein any prior arrangement.

In the embodiment shown in the drawing it is supposed that if there areseveral combustion chambers ch arranged for instance around thecompressor, it is possible to distribute several chambers b and f fedrespectively by pipes at and e in alternation along a circle coaxialwith the axis of the compressor.

In order to allow a better understanding of Figs. 1 and 2, thedeflecting channels have been illustrated as lying outside the spaceoccupied by the combustion chambers, but as apparent from Fig. 3 that isa transverse cross-section of Fig. 1 through said combustion chambers,these pipes a and e may be housed without any difficulty between saidchambers, said arrangement having the advantage of not increasing thebulk in diameter of the fairing of the reaction jet turbines.

Lastly, it will be noticed that the deflection of the gases leads onlyto the provision ofsupplementary pipes and consequently they do notrequire the arrangement in the normal path of the gases of any hindrancethat might be a cause of v a lowering in the efiiciency or of areduction in;

the thrust during normal operation.

Obviously, the forms of execution described have been given out by wayof mere examples and they may be modified chiefly through thesubstitution of technicalv equivalents without widening thereby thescope of the invention.

What I claim is:

1. In an aircraft driven by a reaction jet turbine fed with hot gases bycombustion chambers, braking means comprising a set of by-pass channelsforming an annular arrangement coaxial with the combustion chambers, thealternate channels being connected respectively to the exhaust side ofthe turbine and to the exit of said combustion chambers, said channelsbeing adapted to convey and discharge frontwardly a part of the hotgases from the combustion chambers and a part of the eiiluent from saidturbine and opening each into the atmosphere at the front of theaircraft, and means for simultaneously controlling the outputs of allsaid by-pass channels into the atmosphere.

2. In an aircraft driven by a reaction jet turine having a combustionchamber provided with means for burning fuel therein, a source of airunder pressure connected to said chamber in order to supply it withcombustion air so as to form hot gases, a gas turbine having its inletconnected to the exit of said combustion chamber so as to be fed withhot gases therefrom, and a jet forming nozzle rearwardly directed andconnected to the exhaust side of said turbine, braking means comprising:at least one channel connected to the exhaust side of said turbine andfrontwardly directed, said channel being adapted to by-pass anddischarge frontwardly a part of the eilluent from said turbine, at leastanother channel separate from the former connected to the exit of thecombustion chamber and frontwardly directed, said second channel beingadapted to lay-pass and discharge frontwardly a part of the motive hotgases issuing from said combustion chamber, valve means on each of saidvchannels, and control means for opening and closing simultaneously thevalve means of said channels. v

3. The combination of claim 2 wherein the respective channels areadapted to convey gas outputs which are proportioned to one another inorder to keep substantially constant the rotary speed of the turbine.

4. In an aircraft driven by a reaction jet turbine fed with hot gasesfrom combustion means, the combination of a front exposed surface havinga plurality of apertures therein directed frontwardly and regularlyspaced along said surface, a valve for controlling each aperture, pipemeans for delivering gases from said combustion means to some of saidapertures, other pipe means for delivering gases from the efiiuent ofsaid turbine to the other apertures and means for opening" and closingthevalves for all apertures simultaneously.

MARCEL H. L. SEDILLE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 10 2,280,835 Lysholm Apr. 28, 1942 2,527,732 Imbert Oct. 31,1950

